• Journal of the Korean Mathematical Society
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• v.56 no.3
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• pp.739-750
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• 2019

We proved that finite p-groups in the title coincide with finite p-groups all of whose non-abelian subgroups are generated by two elements. Based on the result, finite p-groups all of whose subgroups of class 2 are minimal non-abelian (of the same order) are classified, respectively. Thus two questions posed by Berkovich are solved.

• Bulletin of the Korean Mathematical Society
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• v.56 no.2
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• pp.365-371
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• 2019

If 𝖃 is a class of groups, denote by F𝖃 the class of groups G such that for every $x{\in}G$, there exists a normal subgroup of finite index H(x) such that ${\langle}x,h{\rangle}{\in}$ 𝖃 for every $h{\in}H(x)$. In this paper, we consider the class F𝖃, when 𝖃 is the class of nilpotent-by-finite, finite-by-nilpotent and periodic-by-nilpotent groups. We will prove that for the above classes 𝖃 we have that a finitely generated hyper-(Abelian-by-finite) group in F𝖃 belongs to 𝖃. As a consequence of these results, we prove that when the nilpotency class of the subgroups (or quotients) of the subgroups ${\langle}x,h{\rangle}$ are bounded by a given positive integer k, then the nilpotency class of the corresponding subgroup (or quotient) of G is bounded by a positive integer c depending only on k.

• Communications for Statistical Applications and Methods
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• v.27 no.2
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• pp.241-254
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• 2020

This study proposes generalized models of joint latent class analysis (JLCA) for longitudinal data in two approaches, a JLCA with latent profile (JLCPA) and a JLCA with latent transition (JLTA). Our models reflect cross-sectional as well as longitudinal dependence among multiple latent classes and track multiple class-sequences over time. For the identifiability and meaningful inference, EM algorithm produces maximum-likelihood estimates under local independence assumptions. As an empirical analysis, we apply our models to track the joint patterns of adolescent depression and anxiety among US adolescents and show that both JLCPA and JLTA identify three adolescent emotional well-being subgroups. In addition, JLCPA classifies two representative profiles for these emotional well-being subgroups across time, and these profiles have different tendencies according to the parent-adolescent-relationship subgroups.

• Bulletin of the Korean Mathematical Society
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• v.38 no.2
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• pp.389-398
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• 2001

Let D be a Dedekind domain with divisor class group Cl(D). We show that there is a correspondence between the set of splitting multiplicative subsets in D and certain subgroups of Cl(D).

• The korean journal of orthodontics
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• v.43 no.3
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• pp.134-140
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• 2013

Objective: To evaluate lower incisor position and bony support between patients with Class II average- and high-angle malocclusions and compare with the patients presenting Class I malocclusions. Methods: CBCT records of 79 patients were divided into 2 groups according to sagittal jaw relationships: Class I and II. Each group was further divided into average- and high-angle subgroups. Six angular and 6 linear measurements were performed. Independent samples t-test, Kruskal-Wallis, and Dunn post-hoc tests were performed for statistical comparisons. Results: Labial alveolar bone thickness was significantly higher in Class I group compared to Class II group (p = 0.003). Lingual alveolar bone angle (p = 0.004), lower incisor protrusion (p = 0.007) and proclination (p = 0.046) were greatest in Class II average-angle patients. Spongious bone was thinner (p = 0.016) and root apex was closer to the labial cortex in high-angle subgroups when compared to the Class II average-angle subgroup (p = 0.004). Conclusions: Mandibular anterior bony support and lower incisor position were different between average- and high-angle Class II patients. Clinicians should be aware that the range of lower incisor movement in high-angle Class II patients is limited compared to average- angle Class II patients.

• The Korean Journal of Elementary Counseling
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• v.10 no.2
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• pp.151-165
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• 2011

This study aims to demonstrate how well SCM analysis, which indicates social cognitive map of categorizing peer subgroups of elementary school students, corresponds with that of teachers. To do this, the subject of this study includes two classes of the 3rd and the 5th grade students in D elementary school in B-gu, Busan city. Over 30 students of each gender in each grade were surveyed with social network questionnaires to collect data. The result of the social network survey was analyzed by SCM 4.0 program to categorize peer subgroups within each class. The categorized peer subgroups were reported to the class teacher. Based on the report, the class teachers observed peer subgroups in classes. After the teachers observed and categorized the students into several peer groups, an analysis was conducted to compare the peer subgrouping by students with that by teachers. The result showed the two were 80% correspondent to each other regardless of gender and grade. If interobserver reliability stays within the range of 80-100%, it is considered reliable. And this leads to the conclusion that peer subgrouping by students' cognition and that by teachers' observation can be regarded quite corresponding. In conclusion, peer subgrouping through SCM is significant when peer subgrouping Korean children, and it appears to be more significant when analyzed considering different variables including gender and grade. Peer subgrouping by girls is shown to be more accurate than that by boys.

• Journal of the Korea Safety Management & Science
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• v.14 no.2
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• pp.237-243
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• 2012

The more the satisfied customers increases in customer satisfaction survey, the more the company has difficultly in improving the customer satisfaction. In addition, the effectiveness of practical application of customer satisfaction survey decreases due to its constitution limitation on its data analysis. To overcome these problems, it is necessary to develop a new method to identify the strategy meanings and find the dissatisfied factors of satisfied customers using the satisfied customers reclassification. This study focuses on the satisfied customer segmentation using Latent Class Analysis. The case study shows that the satisfied customers are divided into three subgroups using Latent Class Analysis and we draw meaning results such as satisfaction and dissatisfaction factors through analyzing each group. This study is expected to play the role as the groundwork for the revitalization of customer satisfaction survey.

• Korean Journal of Social Welfare Studies
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• v.40 no.1
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• pp.197-234
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• 2009

Typological theories of offending postulate that childhood-onset delinquents have a high likelihood of being serious and chronic offenders and that there are a distinct set of risk factors predicting early-onset antisocial behaviors. It is useful to empirically classify children into subgroups based on their deviant behaviors because it helps us to identify unique factors associated with each subgroup. Using the first two waves of the Korean Youth Panel Survey, Elementary School Data, this study aimed(a) to empirically classify 5th graders into latent delinquent subgroups, and (b) to examine the impact of individual, familiar, school, and peer factors on the latent delinquent classes. Latent class analysis yielded three latent classes based on 15 indicators of deviant behaviors - delinquent class, low-level delinquent class, & normative class. The results from multivariate multinomial logistic regression analyses revealed that being male, reporting low self-control, coming from poor family, high association with deviant peers, and being bullied increased the risk of being in the delinquent class. Moreover, low self-control, aggression, domestic violence, low level of attachment to teachers, and deviant peers independently increased the risk of being in the low-level delinquent class compared to the normative class. Based on the study findings, implications for practice as well as future studies were discussed.

• The korean journal of orthodontics
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• v.23 no.3 s.42
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• pp.341-358
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• 1993

This study was investigated to evaluate the morphologic characteristics of deepbite tendency as multiple factors. The subjects consisted of 60 control subjects(male 25, female 35) and 137 deephite patients(68 male, 69 female). The deepbite group was composed of 4 subgroups(Class I 44, Class II div. 1 40, Class II div. 2 13, Class III 40). The mean age was 21.57 year for the control group 21 year for deepbite group lateral cephalograph in centric occlusion were taken, traced, and digitized for each subject. The statistically computerized analysis was carried out with SAS program. The results were as follows ; 1. In deepbite group, saddle angle is lesser than that of normal group. 2. The vertical dysplasia is prominent on anterior lower face and is closely related with mandibular form and inclination. 3. Without consideration of sagittal relationship, the dental factors such as curve of Spee, interincisal angle, U1 to upper lip length were prominent in the deepbite group. 4. Although there were individual variances in the perioral soft tissue profile, the lip presented more protruded pattern. 5. There was no significant difference in hyoid bone position and inclination between normal and deepbite group. 6. The multivariate discriminant analysis between normal and Class I deepbite group showed that curve of Spee, AB-MP angle, interincisal angle, articular agnle were critical in the determination of deepbite as multiple factors.

• Bulletin of the Korean Mathematical Society
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• v.52 no.2
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• pp.367-376
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• 2015

In this paper, we classified finite p-groups G such that $$C_G(x)/<x>$$ is cyclic for all non-central elements $x{\in}G$. This solved a problem proposed By Y. Berkovoch.